Wow, Skonch, what a great project! When I read the first post, it looked like you're talking about a 1/72 or maybe 1/48 scale project, but when I saw your shots of the bridge and the figures, I've gotta say, very impressive! This will be a fantastic display when you're finished.
BTW, Hammer is right, if I were gluing PVC pipe, I'd use PVC adhesive, you should be able to get it at any hardware store. I don't know how well it will adhere the PVC to other materials, though. For something like a PVC to wood bond, for example, I'd probably use contact cement, the kind you apply to both surfaces, let it dry, and then put them together. Only thing is, it's more or less permanent, so if you need to separate the parts, that would be tough. Hence, measure twice, glue once.
Can't wait to see more progess pics!
Regards,
Brad